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Wednesday, November 2, 2011

Touch Toolbox 3.0 - HW and Network

This blog is Part II of the Touch Toolbox blog.

Over here  I'll touch upon HW modifications, the network and server environment from a HW perspective.

I consider all this an integral part of your streaming solution. All this will also make a difference.

1. Power supply
2. Lan optimization
3. SPDIF data link
4. Onboard modifications
5. Server considerations

You really should have a look at it.  You'll also  find some easy to implement tweaks.


I do not have any commercial relations to any vendors or manufacturers
mentioned in the text below. Yep. It's basically free marketing for those
who are mentioned here.

Let's get started.

1.  Power supply

The Touch switching power supply situation can be improved.

Don't be shocked. That would  happen to you even on >1500$ DACs btw.

The stock supply should get replaced with a high quality linaer regulated device.

The stock supply is dimensioned for a 3A load. If you don't use USB disks etc. you'll get
along with 1A supplies.

Though experience shows that's always a good idea to go for overdimensioned supplies.
My commercial PS recommendation would be an S-Booster Power Supply  at around 140€ (currently 230V only) .

The Sbooster filter (a choke and some caps), which they sell also as a seperate unit, I consider one of the key elements here. That filter is put just in the 5V DC line in front of your Touch DC power line.
This filter can be bought as a standalone device for a couple of $.
It even works well on my battery+SuperTeddyReg based supply - between Teddyreg and Touch.

I tend to say, that the filter makes more of a difference than the PS or regulators itself.  I had those TeddyRegs around. I wouldn't go form them any longer.

If you own a nice linear 5V supply already (EBAY sells those around 30$), you should try at least the Sbooster filter.

If you're a DIY minded person you'll find several recommendations on the net for building a similar filters yourself.
E.g. John Swenson made a nice  proposal based on a Hammond choke.

You can also scan other HW and PS modifications supplied by many companies, if  DIY is not your cup of tea:

Just Google:

Welborne Labs
Bolder cables
Teddy Pardo
Paul Hynes Design

(enough of marketing at this point  ;) )


Install my Toolbox first. You might be able to save some bucks
on at least the HW mods. If the SW is done first you'll notice much
less of an impact of the HW mods.

I've done many of the HW mods myself. My experience is that those
mods like decoupling upgrades do generate a little more dynamic sound experience here and there.
If it's worth to spent 250$ to get it done by an external company is another

I'd say a power supply upgrade you should  consider in any case.

Honestly I would have a slight problem to throw in >250$ for a PS upgrade
plus HW mods on the Touch.

2. Network optimization

In theory the your LAN/ethernet connection shouldn't cause any trouble.
If you ask certain "specialists" out there ( you can put me on the list -- I do have a telecommunications engineering  degree myself), there shouldn't be any impact
by the WLAN or LAN.

Those people are correct in a sense that not a single bit gets lost.
And further 20s (depends on sample rate) of data is buffered on the Touch.
So what's the deal. Aren't we on the save side!?!?
Yep - In theory we should!

However. Some people forget though that the buffer continuously need to be refilled and managed. That there is a NIC in front of that buffer.
TCP/IP on its own comes with tons of parameters. Which are by
default not set perfectly. Varying load conditions and other non linearities on the net will cause quite some data jitter. If and how much translates to noise of jitter
on the SPDIF link I can't tell. But that doesn't matter to me at this point.

The other argument of people questioning any ethernet impact is that each and every ethernet jack is galvanical isolated.  Yep. That's right.
There's a little transformer in each of the jacks.
However. Those people tend to forget that there's still a fad ground connection in place.
The ground itself is not isolated! That  ground feeds all network EM/RFI mess right into your device.
They also tend to forget that galvanic isolation doesn't mean HF isolation.

You should know that - my guess - 99.999% of all households don't have an ITU-T compliant grounding in place. The mains ground grid acts like a nice HF distribution network (antennas) and your Touch finally becomes the tip of that antenna. All that also gets through the "backdoors" - over the mains ground - into the other devices.

Let's try to nail it down. I suspect several  sources, that causing a certain impact:

a. Even though the ports are isolated by transformers, groundloops do exist.
    The connectors are not hospital grade like implemented.
    The cable shield feeds the ground into the device.

    Proper grounding in private home networks just does not exists. The cable acts
    pretty much like an antenna feeding HF into the device.

b. Poor connection due to flimsy ethernet jacks or connectors might cause
    a certain negative impact. The connector won't sit tight all the time.
    As a matter of fact on the Touch I experienced exactly that.
    At these high frequencies you can't afford a loose connector or poor
    connections. There'll be all kind of reflections and crosstalk present.

c. Different load conditions on the Touch caused by congestions, changing traffic
    loads, negotiations will do have a non-linear impact and might indirectly
    degrade the audio performance.
    This would get much worse using the internal WLAN connection.
    WLAN uses heavy encryption on top.

d. You're using an old style router.
    I figured and know from feedback that almost any router adds its own

e. You are using rather low quality ethernet cables.
    (This is the normal situation in many households.)

What to do!?!? 

Network tuning for audio purposes was and I guess still is a pretty new subject. At least to me.
I havn't found any source on the net addressing the subject.

This is the situation how it looks to me from a todays perspective:

2.1. Cabling

Look for good ethernet cable.  You wouldn't believe it. The cable and its endpoints can make a substantial difference.

I hear you: "Please not again this audiophile cable terror" this is ethernet and we buffer 20s of music-data.

Here you'll find a review of German Stereo magazine. They concluded that
out of this test not a single cable (quality cable) complied to CAT6 (<250Mhz).
And except one cable not even complied to CAT5. (<100Mhz)
Further they concluded that unshielded cable consistently sounded best.
The German company Meicord made it rank1 in that comparison.
Those Meicord folks figured out certain aspects by now. Key elements are
supposed to be shielding (ground loop -- my guess)   and the RJ45.
(That's what I figured earlier). They  suspect a problem with 
characteristic impedance mismatch (good end/ bad end) of 100R and thus associated reflections. Crosstalk also seems to play a role.

Over here (in german) you'll find some more info about it.
What's missing though,  is an explanation why all this would impact the audio
stream on the other side of the transformer.

Budget advise:

You might want to try high quality cable CAT6A (=<500MHz). U/UTP stands
for Unshielded and S/FTP for Shielded.

 There are e.g. Draka UC900 S/FTP cable with Hirose Plugs TM31!!!
 (TM31P-TM-88P,)  they sell at a couple of $/€ over here in Europe.
 I paid 6-7€ for 1m.

 Note: I did remove the shield of my cable (it's an S/FTP) 2 inches away from the
           connector to avoid a ground loop into the Touch. That puts at least one
           leg of that patch-cable on ground though - and still makes a nice antenna.
           I also cut the 2 power and 2 ground lines. You just need TX+/- & RX +/-

 Advise: Watch out -- many of those cables come with e.g. Hirose TM21 instead
              of TM31 plugs! This can make the difference!

Audiophile advise:

A german company called Meicord was so nice to send me some samples for testing.

The built quality of those Meicord cables is extremely good.
The connectors look and feel rock solid.
My earlier used Drakas/Hirose compared to the Meicord connectors  look and feel much cheaper.
The cable itself is a bit stiff.  Though similar to my Draka UC900.

Now: Most important -- how do they perform?
I plugged a 1m unshielded patch-cord in between the Touch and my Cisco Hub.
I immediately experienced a clearly audible improvement. The resolution increased.
The overtone spectrum gained substance. You'll notice those changes pretty quick on brass instruments and orchestral music. 

The Meicords are again a step up on my Drakas. 

But please - Don't expect a day and night difference! You should experience what I described earlier.
The same experience I made is reported by a number of people. Its effect on different systems seems to be quite consistent.
If you intend to go after the best. Put that cable on top of your wishlist.

2.2 Ethernet Hub on wired networks

 Try a small active ethernet hub/switch in front of the Touch.

 Use a very short high quality unshielded CAT6A patch cable. The hub does
 some signal refreshing. (You wouldn't believe that this makes a difference.) 
 Meanwhile I use a semi-professional Cisco SLM2008 active hub with good
 results. I use it also for TV etc. The Cisco is a little intelligent boy more a bridge
 than a hub. You can even set QoS priorities on the ports.

  If you have a better power supply at hand you might also try that one
  on the HUB!!!

2.3. Ethernet/WLAN  bridging 

Quite some people can't get their network going without using WLAN.

According to my TT recommendation that would be a NoGo. WLAN usage
on the Touch makes a serious difference on soundquality.

I found an intersting solution - so called Wireless Range Extenders.

Those Wireless Range Extenders are almost plug'n play. You don't have to have
an IT degree to get those working.

The nice thing is that these devices usally come with an ethernet port that we can use
for our purposes. You can now connect the Touch via cable to that device and
can use my WLAN mod now.

Those range extenders are powerful special purpose animals. The performance is much more powerful than those WLAN receivers that you'll find in any of your devices.


a. We can run the Touch in wired mode on the last 3ft.
b. We can do the  signal refreshing, as I'm doing it with the Cisco hub
    described above. ( As usual you might want to try a better PS for that extender.)
c. you'll get an overall better WLAN coverage.
d. you can also use e.g. the less busy 5Ghz WLAN band for better and more stable

d. We might still face  dynamic bandwidth changes on the WLAN link.

Have a look at the Amped Wireless High Power Wireless-N Smart Repeater and Range Extender (SR300) (Thx Guidof from SBF  for that hint)
This product comes with 4 LAN ports. You put it right beside your Touch and connect it with e.g. a 3 foot Monster ethernet cable to your Touch.

There's e.g. a Fritzbox FRITZ!WLAN Repeater 300E (no idea if these are sold overseas) that comes with just one LAN port (of course you could connect a hub here, if you'd need more ports) . The FritzBox comes with DualBand WLAN 2.4 and 5 GHz - You'd be able to use the 5GHz band.

Note: Please, let me know if there are better devices then above out there - I just quickly picked those whithout doing an in-depth market research.

Folks. It's really not that expensive or complicated.

The great side effect -- beside using them for our special streaming network purpose -- is that you'd for sure improve your overall wireless coverage and throughput in the house.

I might give it a try by myself. You never know. It might beat my current cable setup.

3. SPDIF via COAX or Toslink

This is IMO one of the key subjects on the HW side. You wouldn't believe how much impact this SPDIF link can have.

If you don't have your DATA link, the SPDIF link in particular, under control you'll face a rather high impact on your sound experience.

The SPDIF link can really be a nasty bottleneck.

Let's discuss Toslink first.

Toslink sounds OK if you use top quality glassfiber cable. (e.g. Lifatec Silflexx Glass Toslink). The biggest advantage is its great RF rejection/galvanic isolation.
You won't find anything better than that.

I recently figured that one of the key issues of Toslink is its poor implementation.
It IMO got such pretty bad rep because manufacturers don't put much focus on it anymore. The Toslink receivers and transmitters are active elements, which
transform the digital datastream twice.

If you look at e.g. the SB Touch transmitter, you won't find a buffer and decoupling cap at the transmitter. Power will not be stable and distortions can easily enter the datastream.
I changed that.  On both ends. I hooked up 220uf OSCONs on each side and a little 0.1 MKP capacitor.

Since then I'm running Toslink.

A well done COAX implementation (the whole link from sender chip to receiver chip)  might beat the Toslink connection. ( I tried several pulsetransformers and they all caused a different signature to the sound). There are manufacturers selling transformer coupling as "isolated". That's misleading.
These pulsetransformers lowering distortions in a certain area. Many of them (RF/EMI) just jumps over the transformer.
The real life problems with such an implementation are more then challenging.
There are galvanic RF connection issues, rather poor 75R characteristic impedance implementations, unmatched terminations causing severe reflections, poor connectors, poor cables, cable lengths discussions asf. asf.

All those above issues will cause extra jitter and noise. And that jitter adds to the receiver jitter generated by the receiver chip itself.
As far as I can judge the Logitech part of that implementation looks pretty basic. They skipped a pulsetransformer on the RCA output, as you'd find it on high quality SPDIF implementations. The RCA jack is not 75R compliant . It runs roughly at 35-50R usually causing nasty reflections. Inside the Touch the path follows more connectors, soldering joints asf. All this will cause more reflections and signal degradation.
These are the first very obvious shortcomings. Any 75R compliant jack  BNC or RCA would have been the better choice.

Three areas can and should be improved:

1. Galvanic isolation (only needed if the DAC won't come with a pulsetransformer on the input) - you still face lowered EMI/RF distortions though.
2. impedance mismatch
3. power supply / decoupling

Don't get fooled by marketing around super expensive SPDIF cables. Trust me.
The endpoints are usually the main problem, not the cable.
A quality el cheapo Belkin with the well implemented endpoints usually would do.

Recommended SPDIF mods:                     

I applied some modifications, resulting in  a worthwhile, I'd even call it, serious improvement.

a. improving PS of Touch incl. choke filter (CLC/PI) and all electrolytic caps on the board
    as a base mod. This has an indirect impact also on that digital ouputstage.
b. direct wiring of spdif cable to the mainboard (bypass Touch RCA and and internal comb
    connector . I cut the link at the comb connector off).
c. introducing a reference pulsetransformer  (e.g. Nevawa S22160 Digikey)
    (on the receiver side (DAC) only and not more than one per link!!)
    Be careful with those transformers. They all will add a different signature
    to the sound. I tested around 6 of them. Some were called audiophile at audiophile
    prices and failed to prove it in my setup.
d. using a good quality but not overexpensive 75R coax (12inch). If you pay
    more then 10-20$ you IMO paid to much.
e. I pushed it even further: Both ends are hardwired now - no more
    connectors on the link. That's IMO as good as it can get.
f. My Toslink receiver/transmitter got some caps soldererd to its power pins. 

4. Onboard modifications

Once you have the Touch disassembled, and you consider yourself a rather experienced HW tweaker, you can continue by applying certain  onboard modifications.
Most of the professional modification companies will do pretty much
the same stuff. Better decoupling, better regulation, better clocks.
Usallully at >250$ ( e.g. Audiocom) . Some of those even offer rather esoteric Bybee mods.

Caad from Squeezebox forums did some extensive baking on the board.
He even had access to high quality measurment equipment to verify the
results of his mods.

To work on those highly integrated boards with all its tiny parts and
multilayer boards needs a lot of experience and good tools.

You don't seriously want to fry your 300$ invest for swapping a cap or two. ;) 

4.1 Analog Output Modification ( For DIY enthusisats)

The Touch comes with a rather decent DAC an AKM AK 4420 inside.
If you've got all mods from above applied it'll sound quite good to be honest.

As usual you can work on its decoupling, output stage and powersupply.
I'm not sure if a clock upgrade would make much sense. The DAC has its limits.
You need to be careful not to waste too much money on it.

I just removed the coupling caps, which do heavily impact the signal path.
That mod IMO is a must for those want to run the Touch on its analog outputs.
 It really lifts the output two notches up.

Again this is something for someone experienced.

4.2 Decoupling

I won't go deeper into the subject for now. Applying OsCom Caps in "Lampizator" style will noticeably improve the performance of your device.

That's btw one of the main mods that all those professional modifcation companies apply.

I'll continue to add some more information sooner or later. Above referenced proposal of Caad pretty much covers the exercise though.

5. Server

That's also a nice subject. Let's discuss which server and server setup to choose for best performance!?!? I'm taking about sound and not processing power. ;)

Server!?!? Why are we talking about a server here. Yep. Many of you wouldn't expect that
a server could be a potential tweaking target. To be honest I wasn't that expecting either.

I did  compare many of those setups, I can tell you they all "sound" different.
I know. That's not funny.

I don't want to speculate why it makes a difference.  We're talking HW, OS, drivers and applications. Somehow anything can make a difference.

Now. What's my personal solution.

I'd differntiate between 

a. NAS (usually a very slim  Server-Linux) running LMS
c. Windows 7
d. Desktop Linux
e. Server-Linux

5.1 Type of server

I prefer the flexibility of a "normal" PC running the server software.
I can do lot more stuff with it than using a stiff NAS.
A NAS usually lacks also months/years behind of normal developments
on the SW side. You won't see many upgrades taking place.
I do consider the support life-cycle of those NAS devices a major problem.
To me these NAS are black holes. I keep my hands off those devices. (I made my experiences). Also forget ARM (RPI/Cubi/Udoo/...) devices. As soon as you want them to run a challenging task (database rescan, realtime DSP, transcoding, sampling)they run out of steam.

If I talk "normal" PC, I'm talking about quiet & fanless machines.  These are IMO even much much better then Quad Core Wand /Udoo and alike. Obviusoly you can use them aslo as playback client. Beside that you'll have much less hazzle with SW.

A headless type PC like a Zotac ZBOX  ID82 ( core i3) /AD04 or NUC or similar, which comes with a real CPU - please avoid the ATOM or ARM stuff - could be a pretty good choice. You'll usually have (e)Sata and USB3 ports at roughly 250$-350$.

If you consider to run also a DLNA server feeding your TV set with HiRez videos. You might  consider something that comes with muscles. You need
to have some air left for heavy realtime transcoding work.
I'm currently running an i5 processor with 8GB RAM and SSD as
system disk. PS is a Seasonic 400W fanless PS. ARM on Atom will fail at this point!!

As a goody I'm running and IBM 1000 pro network adapter (PCIe). You'll find
them used for a couple of $ out there. It really made a difference.  

Beside that...

Make sure that you have you MB drivers updated.

If you manage -- don't use a 5 year old leftover MBO/PC.

What I also like is the WD Western Green 2TB 2,5'' HDD. It's 15mm high!!
It's quiet and small.

If you don't have a budget issue I'd recommend to go for 512 GB Samsung SSD.
You'll get >1200 flac CDs on it. That should be more than sufficient for most
of you out there.

AND: Always count a 2nd/3rd set of disks into your budget. Even though it hurts.
          You need healthy backup disks. Read my "Silent Death post"

5.2.  Choice of OS

I experienced that all OS sound different due to whatever reason.

The typical suspects. Inefficiency of OS (incl. networking stack) and driver issues.

There were times I went from Linux to Windows 7 to Windows 8.

Now I'm back to Linux - Ubuntu Server 14.04 minimal with custom rt-kernel.

Most of you will run a Windows system as server.
I highly recommend to try some of the known OS optimizations, that you'd
use if you'd use the PC as transport.
Go for Windows 8 ( better then Windows 7) and start e.g. Fidelizer.
You'll notice slight differences.

6. Wrap UP

I hope I could get you at least some ideas on the HW and network side.
With some of the HW mods you might gain rather substantial improvements.
But again. The better your DAC, the less impact you'll notice. The more bottlenecks you've got in the chain - the less impact you'll notice.

The SW and HW mods that you'll find described over here make a nice sounding, future proof and still affordable streaming solution.

Looking into your overall todays and near future server and network situation makes pretty much sense too.

Consider that you'll going to hook up  more and more streaming devices (TV, BluRay player asf) to it. All these will put higher demands on your server and network.



  1. Hi Klaus

    Thanks for adding me in your Blog.

    Best Caad

  2. Dear Klaus!

    I have had some happy months with your V2.0! I implemented a big part of it. I got back to check news now and then, and now, I see, that you have 3.0 out - a bit more convenient, but more importantly, even more mods. I will give it a try as soon as I can.

    However, there is one question: If I remember well, you recommended Windows XP as Server OS in some comment a few months ago. It seemd to outperform any Linux setup. My server runs on a Windows XP notebook and it performs quite well.

    Anyway, I do not know, if it would sound substantially better on Windows 7, that you recommend now.

    Can you give us a hint on that? Is Windows 7 better than XP?

    Upgrading from XP to 7 would bring along quite some expenses and even worse, it needs time, until everything is in place again. So if it sounds about the same as XP, I will stick to this - as I am pretty happy with it until now.

    And as a final but probably the most important word: Thanks a million!!! I see that you took away your donation buttom, of which I made use twice, if I remember well... Is it hidden somwhere? Anyway I would recommend it warmly to any fellow who uses your mods!

    Cheers! Urs

  3. Dear Klaus,

    I use Tplink as a WLAN extender for the Touch or other Raspberry Pi kind of computer.

    It features a USB plug for PSU along with small footprint.
    You can power the extender from the Touch USB connector making it a safe and cost effective solution.

    Hope it helps.

    Best regards,

  4. Powerline adapters

    The author mentions using a wireless bridge in section 2.3 as a potential hybrid streaming solution to allow the SBT to switch off the wireless and connect by ethernet to the bridge unit instead.

    An alternative to a wireless bridge is using powerline adapter which route their signal across the internal electrical wiring.

    How does signal interference compare in general to routing across a home's electrical wiring than to routing via wireless?

    Specifically, how do powerline adapters compare to using a wireless bridge in terms of audiophile performance with the TT3.0 mod?